CTIS Parts

[Hwhomes]

Here is a pic of some type of valving fastened to the back side of the frame crossmember behind the rear axle. There appears to be some part or cap missing. Would this be the reason for the rushing air sound and the failure of the rear tires to deflate?

 

[Coffey1]

I would like to suggest that you put a jack under it and get weight off flat not good on tire sitting there flat.

 

[Suprman]

That's a quick release valve. It's just missing the rubber boot. Does air come out when you are trying to fill or dump air?

 

[Hwhomes]

What is a rubber boot? Air pours out when dumping air. Seems it should have some type of cover or connect to something. Ideas?

I've installed the new wheel air hose, thx Suprman, and all tires inflate and deflate.

At at highway setting tires have 55 lbs per my gauge and just under 20 at the sand setting. I'd expect more pressure at highway setting. Is this a typical air pressure?

 

[Coffey1]

55 is where my 5 ton runs

 

[Suprman]

It's supposed to have a rubber duckbill thing on it. That's where air comes out of when lowering pressure. 55-60 psi sounds about right.

 

[Hwhomes]

I'm guessing it's designed to let air out and keep debris from entering? Source for replacement or a picture?

 

[PBR street gang]

Hello Sir,My LMTV is down. Do you know what type of fitting the air (CTIS) system uses? I have what I think is a failed diaphragm on a rear axle quick valve. I wanted to cap the lines to isolate the tires, then cap the quick valve to see if I could repair or find a replacement for it. The fittings look like JIC but the taper is wrong. I am also not sure how to shut off the quick valve, and if I do so, is part of the quick valve body removable for repair? Any help would be appreciated. Thank you .

 

[Suprman]

Whats happening exactly? Are the tires deflated?

 

[PBR street gang]

I have a flashing 4 lights on the CTIS modual and the left rear tire dumps air from the air discharge on the quick valve. I have some seepage from other locations in the wheel but nothing like the dump from the vent.

 

[Hwhomes]

You can put a valve stem in the tire valve. That will allow you to fill/deflate the tire independently of the CTIS system. It will also isolate that tire from the CTIS system, in effect making it inoperable.

 

[Suprman]

So air leaks out of one wheel when the truck is off? 4 flashing lights can indicate a leak somewhere. You need to be more descriptive.

 

[PBR street gang]

Regardless if the truck is running or not, air will dump from the left rear tire out of the vent on the quick valve on the rear axle. I have soaped the tire and hose fittings and I find only a modest leak around both wheel valves. I can keep ahead of the leak in the Run Flat setting, but the tire will deflate when the Run Flat times out. I suspect the diaphragm in the quick valve. What else could cause the air from the tire to exit the quick valve?

 

[Suprman]

Sounds like air is leaking out thru the wheel valve. The quick release valve is just doing its job venting the air. Take the line to the hub off from the wheel valve and see if air is coming out. Take the valve apart. Maybe just dirt in there or it might be corroded inside and need replacement. Should be an easy fix. The 4 flashing lights may be related to something else though.

 

[PBR street gang]

If the wheel valve does need parts, would they be commercially available? Also, what does the kneeling valve do?

 

[PBR street gang]

This LMTV came from Fort Drum and corrosion from salt is significant on some components.

 

[Suprman]

I have all the parts. Some of the Drum stuff may have been used in Sandy and has saltwater corrosion. Pull up your cab mats and look at the floors. The kneeling valve is a screw head thing that you can use to dump air for rapid height reduction when loading the truck onto some type of transport. I don't like them they can be leaky. Usually a slow leak though.

 

[PBR street gang]

I am afraid that may be the case. The floor was so rotted that the accelerator pedal fell off. Is the wheel valve a check valve? Where is the valve that holds pressure? Is it all the way in the front at the manifold?

 

[Suprman]

It's on the wheel. 2 air lines going to it. That's what holds the air in. Watch out for wire harness corrosion you will get electrical gremlins.

 

[PBR street gang]

Thank you. I will start with the wheel valve. I could not find anything in the manuals about servicing the wheel valves other than "replace". Is there a temp fix (isolation) to a wheel valve failure other then a tire change?